A photosensor lens described in Patent Document 1 has been known as a photosensor lens including a light emitting lens portion and a light receiving lens portion formed integrally with each other. In this conventional example, the lens has a cuboidal shape with flat surfaces on the two opposite sides, and is formed to have convex lens surfaces provided at a flat surface portion facing the inside of a case for a light emitting element and a light receiving element disposed inside the case.